While natural fiber fillers for use in polymeric materials have attracted some interest as potential replacements for more traditional reinforcing materials, such as fiberglass, commercialization of such products has been limited. Extracting natural fibers from renewable plant sources in a sufficiently purified form has been a challenge, as has identifying natural fibers with mechanical properties comparable to man-made reinforcing materials. Known sheet materials formed from polymeric material commonly involve mixing chopped natural fibers such as wood with a polymeric material with the two constituents being molded into an intermediate or final product.